This is a Ruby tree! It shows every object from the Ruby Programming Language in a tree format.

key? 

        # Thread.key?

(from ruby core)
---
    thr.key?(sym)   -> true or false

---

Returns `true` if the given string (or symbol) exists as a fiber-local
variable.

    me = Thread.current
    me[:oliver] = "a"
    me.key?(:oliver)    #=> true
    me.key?(:stanley)   #=> false

This is MURDOC! A Ruby documentation browser inspired by Smalltalk-80. It allows you to learn about Ruby by browsing through its class hierarchies, and see any of its methods.